Plug-in electric heater construction



Aug. 1967 D. M. CUNNINGHAM 3,336,466

PLUG-IN ELECTRIC HEATER CONSTRUCTION Filed Feb. 12, 1965 2 Sheets-Sheet 1 INVENTOR. DONALD M- G UNNINGHAM 8 1967 D. M. CUNNINGHAM 3,336,466

PLUG-IN ELECTRIC HEATER CONSTRUCTION Filed Feb. 12, 1965 2 Sheets-Sheet 2 INVENTOR. DONALD M- CUNNINGHAM A TTORWA 5 United States Patent Ofltlce 3,336,465 Patented Aug. 15, 1967 3 336,466 PLUG-IN ELECTRIC HEATER CONSTRUCTION Donald M. Cunningham, Pittsburgh, Pa, assignor to Edwin L. Wiegand Company, Pittsburgh, Pa. Filed Feb. 12, 1965, Ser. No. 432,091 tClaims. (Cl. 219451) ABSTRACT OF THE DISCLOSURE A range top electric heater assembly wherein the electrical connections are provided, by electrically conductive members resiliently biased to interengagement'and wherein abutment means yieldably resist separation of the current conductive members.

The present invention relates to electric heaters, more particularly to plug-in electric heaters of the range top or surface-type, and the principal object of the invention is to provide new and improved heaters of such character.

While the plug-in type range top heater disclosed in application Ser. No. 421,745, filed Dec. 17, 1964, now Patent No. 3,246,123, has been crowned with great commercial success, field results have pointed out one deficiency: In a relatively small number of cases, the accumulated tolerances between various parts have made it possible for the element terminal end portions to make less than complete engagement with the current-carrying contact members within the terminal block. When this occurs, arcing can quickly damage the interengaging contact surfaces.

By use of the present invention and once proper engagement between the element terminal end portions and the contact members has been established, the unintentional loss of such engagement is virtually impossible. Thus, long trouble-free contact life is assured. These and other advantages will readily become apparent from a study of the following description and from the drawings appended hereto.

In the drawings accompanying this specification and forming a part of this application there is shown, for purpose of illustration, an embodiment which the invention may assume, and in these drawings:

FIGURE 1 is a top plan view of a range top heater assembly constructed in accordance with a preferred embodiment of the present invention,

FIGURE 2 is an enlarged view, partially in section and partially in elevation, and generally corresponding to the line 22 of FIGURE 1,

FIGURE 3 is a fragmentary enlarged view similar to FIGURE 2 but with parts on the near side removed to show the underlying structure, and

FIGURE 4 is a further enlarged perspective view of a detail seen in FIGURE 3.

With reference to FIGURES 1 and 2, the present invention comprises a heating element herein disclosed to be of the sheathed embedded type. Briefly, such an element comprises a tubular sheath filled with a compa'cted heat-conductive electric-insulating material in which is embedded an electric resistor member. The resistor preferably terminates short of each end of the sheath and each resistor end is mechanically and electrically connected to a respective terminal pin, each of which extends beyond a respective sheath end, for a purpose to appear.

In the present embodiment, the intermediate portion of the sheathed element (that portion which enclosesthe resistor) is formed to provide a plurality of convolutions forming a generally plane heating surface 11 which is normally supported in a generally horizontal position by the range top 12. Respective terminal ends of the heating element 10 are bent downwardly and outwardly (in the position of parts viewed in FIGURE 2) to provide generally parallel, spaced-apart terminal leg portions 13 and 14 which are spaced below the heating element surface 11 and which project generally horizontally in side-byside relation beyond the periphery of such heating surface.

Suitable means are provided for connecting the element terminal leg portions 13, 14 together and such means may comprise a sheet metal strip 15 extending between and welded, crimped or otherwise secured to respective element terminal legs. Alternatively, strip 15 may be secured to but one element leg portion and may have sliding connection with the other via an oversize aperture formed in the strip for passing such other leg portion. In any event, strip 15 functions to maintain the element terminal leg portions in the desire spaced relation despite expansion and contraction of the element during heating and cooling cycles.

The means presently employed for removably supporting the heating element 10 in position wherein its heating surface 11 may underlie and support a vessel to be heated is as follows: A ring-like member 16 having a radially outwardly turned flange portion 17 and a radially inwardly turned flange portion 18 is adapted to be positioned over an aperture 19 formed in the range 12 so that the flange portion 17 overlies the upper surface of the range top. Although not shown, the ring member 16 may carry the usual spring clips or the like which resiliently retain it assembled with the range top and generally centered within the range top aperture 19. It should be understood that while the ring member 16 is herein disclosed as being separate from the range top, such member may, if desired, be eliminated by forming the radially inwardly turned flange 18 as an integral part of the range top 12.

A shallow tray, or drip pan 20, is adapted to be removably carried by the ring member 16 in position to underlie the element heating surface 11 when the latter is in its normal, full line position seen in FIGURE 2. This tray, or pan, serves to reflect the heat radiated downwardly by the heating element and also serves to catch any drippings or overflow which may occur during cooking. Pan 20 is formed with a radially outwardly turned flange portion 21 which overlies the ring member flange 18 to thus support the pan in position. A portion of the pan is cut away at 22 to pass the aforementioned element terminal legs 13 and 14.

Means 23 known in the art as a spider, underlies the heat-generating portion of the element and supports the latter in its normal position. Although forming no part of the present invention, spider 23 is preferably formed of a length of metal strip positioned on edge and formed to a generally triangular configuration to provide a plurality of interconnected legs. Any suitable expedient may be employed to secure the spider to the underside of the element heat-generating portion, the spider resting upon the drip pan flange 21 when such pan is assembled with the ring member 16.

As previously mentioned, each terminal end of the heating element has a terminal pin protruding axially therefrom and as seen in FIGURE 3, a terminal pin 24 protrudes from the element terminal end 13. An identical pin, of course, protrudes from the element terminal end 14. The free end of each terminal pin aforesaid is provided with a transversely projecting shoulder and as herein shown, such shoulder is provided by respective sheet metal loops 25 welded to respective terminal pin free ends. Each loop 25 provides vertically spaced arcuate surfaces 26, 27 for engagement with contact means later to be described.

Secured in any suitable manner beneath the range top 12 to one side of the opening 19 is a bracket 28 which supports a dielectric terminal block 29. In the present embodiment, block 29 has a pair of elongated passages 30 I (only one of which is seen in FIGURE 3) extending therethrough in side-by-side relation for receiving respective element terminal ends 13, 14. For a purpose to appear, a central boss 31 extends across each passage 30 and a pair of opposed projections 32 are formed in each block passage adjacent respective bosses.

Removably disposed in each block passage 30 is a. spring contact 33 having a generally hairpin-like configuration (see FIGURES 3 and 4). Each spring contact is preferably formed of spring strip material of a width to closely fit within respective block passages. The bight portion 34 of each contact 33 is proportioned to closely fit between the passage projections 32 with the bight in. abutment with the boss 31. Inwardly projecting, struck out tabs 35 are formed in respective contact legs 36 for engagement with adjoining portions of the boss 31 to retain each contact within its block passage. The free ends 37 of respective contact legs 36 are disposed in diverging relation to provide a tapered pocket in which respective element terminal ends 13, 14 and more specifically the loops 25, may be inserted. Each contact bight portion has a lug 38 welded or otherwise secured thereto providing for the connection of an electrical lead (not shown) to respective contact members.

With the construction thus far disclosed, it is to be understood that element may readily be dissembled from the range top by tilting it to the phantom line position shown in FIGURE 2 and shifting it to the right to withdraw its terminal end portions from the terminal block passages and from engagement with the contact members 33. Reversal of the above operations effects reassembly of the element with the range top.

During disposition of the element 10 in its normal heating position, the ideal relationship between the contact members 33 and the terminal pin loops 25 is illustrated in FIGURE 3. Unfortunately, however, an accumulation of tolerances may result in one or both of the loops 25 being positioned closer to the diverging contact member leg portions 37. Under extreme conditions, it has been found that vibration can cause one or both of the loops 25 to partially emerge from between the contact member legs 36 thus resulting in poor electrical contact and a resultant destructive arcing. To insure against such occurence, the following construction is employed:

As best viewed in FIGURES 3 and 4, each contact member leg 36 has an inwardly directed abutment or protuberance 39, such abutments being in opposed, facing relation and disposed adjacent the diverging leg portions 37. As will be evident, abutments 39 will engage behind respective terminal pin loops 25 during movement of the element terminal ends 13, 14 to the right and yieldably resist withdrawal of such element terminal ends 13, 14 from engagement with the contact members. Ease of disassembly of the element 10 from the range top will, however, be substantially unaffected since the tilting movement of the element during removal tends to pry the contact member legs 36 apart.

While an element having but two terminal ends 13, 14 has herein been disclosed, it will be understood that the invention is applicable to elements having any number of terminal ends. For example, a common type of element having four terminal ends could be used with a terminal block having four passages in which respective contact members are disposed.

In view of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. A range top heating unit comprising an elongated sheathed electric heating element having an intermediate heat-generating portion providing a generally plane heating surface removably supported by the range in a generally horizontal position for underlying and supporting a vessel to be heated and having terminal end portions extending from respective ends of said intermediate portion for conducting electrical energy thereto and said terminal end portions being disposed beneath said heating surface and projecting generally horizontally in side-by-side relation beyond the periphery of said heating surface, a dielectric body carried by the range beneath the range top and spaced to one side of said element heating surface adjacent the free ends of said element terminal end portions, gripping means carried by said body and providing respective opposed surfaces resiliently biased toward each other to grip respective element terminal end portions therebetween and place such portions in an electrical circuit, and abutment means in part carried by said element terminal end portions and in part carried by said gripping means and interengaging to yieldably restrict withdrawal of said element terminal end portions from said gripping means.

2. The construction of claim 1 wherein each element terminal end portion provides a transversely extending shoulder and wherein said gripping means has protuberances engageable behind respective terminal end portion shoulders for the purpose aforesaid.

3. The construction of claim 1 wherein said gripping means comprises hairpin-like resilient members each having a pair of legs in opposed, side-by-side relation and providing respective surfaces.

4. The construction of claim 3 wherein each element terminal end portion provides a transversely extending shoulder and wherein each member leg has a protuberance engageable behind respective terminal end portion shoulders for the purpose aforesaid.

5. The construction of claim 4 wherein said hairpin-like members are disposed with their leg free ends directed toward said element, wherein the free ends of said member legs are in diverging relation to provide a tapered pocket for guiding respective element terminal end portions to position between said legs, and wherein each member leg protuberance is adjacent a respective member leg diverging portion.

References Cited UNITED STATES PATENTS 3,016,444 1/1962 Iasionowski 219-451 3,021,414 2/1962 Sand 21945l 3,246,123 4/1966 Ammerman et al. 219-451 RICHARD M. WOOD, Primary Examiner.

L. H. BENDER, Assistant Examiner. 

1. A RANGE TOP HEATING UNIT COMPRISING AN ELONGATED SHEATED ELECTRIC HEATING ELEMENT HAVING AN INTERMEDIATE HEAT-GENERATING PORTION PROVIDING A GENERALLY PLANE HEATING SURFACE REMOVABLY SUPPORTED BY THE RANGE IN A GENERALLY HORIZONTAL POSITION FOR UNDERLYING AND SUPPORTING A VESSEL TO BE HEATED AND HAVING TERMINAL END PORTIONS EXTENDING FROM RESPECTIVE ENDS OF SAID INTERMEDIATE PORTION FOR CONDUCTING ELECTRICAL ENERGY THERETO AND SAID TERMINAL END PORTIONS BEING DISPOSED BENEATH SAID HEATING SURFACE AND PROJECTING GENERALLY HORIZONTALLY IN SIDE-BY-SIDE RELATION BEYOND THE PERIPHERY OF SAID HEATING SURFACE, A DIELECTRIC BODY CARRIED BY THE RANGE BENEATH THE RANGE TOP AND SPACED TO ONE SIDE OF SAID ELEMENT HEATING SURFACE ADJACENT THE FREE ENDS OF SAID ELEMENT TERMINAL END POR- 